Dynamo-electric machine.



W. B. KOUWENHOVEN & G. B. WILKINS.

DYNAMO ELECTRIC MACHINE APPLICATION FILED JUNES. 1910.

991 ,787, Patented May 9, 1911.

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ilNlTEl SA Hg ATENT @EFTCE WILLIAM BENNETT KOUWENHOVEN AND GEORGE B.WILKINS, OF NEW YORK, N. Y.

DYNAIVIO-ELECTRIC MACHINE.

comer.

Specification of Letters Patent.

Patented May 9, 1911.

Application filed June 8, 1910. Serial No. 565,781.

To all whom it may concern:

Be it known that we, WILLIAM B. Kon- \VENHOVEN, a citizen of the UnitedStates, residing at Brooklyn, county of Kings, city and State of NewYork, and GEORGE B. VVILKINS, a citizen of the United States, residingat Morris Park, county of Queens, city and State of New York, haveinvented certain new and useful Improvements in Dynamo-ElectricMachines, of which the following is a specification.

This invention relates to dynamo electric machines and has referencemore particularly to direct-current, electric motors of the typeemploying a shunt field winding, that is, either shunt-motors or motorshaving a compound field winding.

The invention is directed to the provision of certain improvements inconnection with motorsof this type the object of which is to moreeffectually protect the motor from injury due to fluctuations of theline voltage.

The invention is of particular utility in connection with direct-currentmotors having a shunt field winding and used in electric railwaycircuits. Most of the electric railways in this country employ directcurrent, the voltage of which is supposed to be maintained constant atabout 550 to 660 volts. It is well known, however, that this voltage issubject to wide fluctuations, particularly on large systems where thetrain loads are very heavy, and may often vary as much as 150 volts. Insuch systems it is very common to employ shunt-motors for variouspurposes in the power-plants, repair barns, shops and stations, as forinstance in running elevators, pumps and the like, and in the operationof these motors, great difliculty has been experienced due to the effectof these pronounced changes of voltage occurring from time to time. As aresult of such changes in the potential across the lines of a circuit,the armatures of the shunt-motors have been burned out and thecommutators have been so injured as to result in the loss of the use ofthe motors for substantial periods and the necessity of making extensiverepairs. Such fluctuation of the voltage of the system is believed tocause a high potential surging in the system and may lead to a hightension discharge from the field of the motor through the armature withconsequent injury to the latter, for instantaneous voltages of over 1000volts have been indicated by instruments in a circuit the normal voltageof which is but 650. Also, motors having shunt field windings arefrequently used in driving machine tools such that the load comes on themotor suddenly and so heavily that the rotation of the armature ismomentarily checked or even entirely stopped; when this occurs therefollows a rush of current through the armature due to the cutting downof the counter electro-motive force.

The present invention aims to provide means whereby the danger of injuryto the motor in this Way may be effectually guarded against.

It consists in the utilization of a chokecoil or inductance forobstructing the passage of momentary rushes of current and connectingthis choke-coil in the armature circuit of the motor so that it willprotect the motor both against a rise of voltage and a sudden rush ofcurrent resulting from such rise of voltage or from any other cause suchas a fall of the counter electro-motive force.

The invention is illustrated in the accompanying drawing which shows themotor and the connections thereto diagrammatically.

The lines 1 and 2 indicate mains of a diroot-current circuit, in whichthe voltage is normally maintained substantially constant, such as wiresconnected to the mains of a direct-current railway system operating at650 volts. A. shunt-m0t0r is connected in circuit between the lines 1and 2 by the wires 3 and at, its armature being indicated at 5 and itsfield at 6. A choke-coil or inductance is shown at 7 connected in thearmature circuit of the motor, that is, it is connected in series withthe armature and it and the armature are connected in parallel with thefield coils. As thus arranged, the choke-coil 7 will protect thearmature 5 against injury resulting from a sudden and pronounced rise ofvoltage or a rush of current due to such a rise of voltage or to anyother cause, such as a pronounced decline of the counter electromotiveforce of the motor or a discharge from the field coils through thearmature. This means for protecting a shunt-wound direct-current motorconsisting in connecting a choke-coil in the armature circuit is onewhich is inexpensive to manufacture and readily installed and Thisspecification signed and witnessed, this sixteenth day of May, 1910.

WILLIAM BENNETT KOUWENHOVEN. Witnesses HERMAN LEHMAN, CHAS. A. KENMORE.This specification signed and witnessed, this 25th day of May, 1910.

GEORGE B. WILKINS. lVitnesses \V. E. VVILKINS, S. V. Kasonnn.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. C.

